Practical Application of Large Eddy Simulation to Accessible Combustion Chemistry Physics

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Title Practical Application of Large Eddy Simulation to Accessible Combustion Chemistry Physics
Creator Isaac, Benjamin; Smith, Sean; Parente, Alessandro; Thornock, Jeremy; Smith, Philip
Date 2012-09-06
Abstract Combustion regimes approaching the unity Damkohler number present challenges due to the increase in turbulent intensity and the slowing of reacting time scales due to chemistry dilution and temperature decrease. The physics of these particular systems of interest provide interesting dynamics in which classic models, such as flamelets, can no longer adequately describe the complex interactions of the system. Many combustion technologies using flameless combustion are emerging and the demand for adequate modeling techniques of these regimes, generally characterized by the unity Damköhler number, are increasing. The chemistry in these systems contains slower reaction time scales which can be accounted for by Large Eddy Simulation (LES) computations. In order to physically define the chemical scales which are accessible on the LES grid, we present a novel approach for the Damköhler definition. FoxFox [7] introduced a method for calculation of the reacting time scales of a system through the eigenvalue decomposition of the source term Jacobian matrix. As a continuation of this work we demonstrate the ability to find the meaningful reacting time scales by performing the decomposition on a reduced set of principal species determined by Principal Variables Analysis (PVA). Through this new methodology we conclude with a demonstration of an a priori analysis which can be done during model selection or model development which clearly defines the accessible physics when using Large Eddy Simulation by providing from the analysis the Damköhler numbers accessible on the LES grid for a given reaction time.
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Date Created 2013-02-14
Date Modified 2013-02-14
ID 14345
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